A wireless network generally includes several Access Nodes (ANs) and several user devices. For a correct network operation, the user devices transmit UpLink (UL) reference signals, hereafter denoted beacons, which are received, detected and decoded at one or more access nodes. The access nodes and/or the network can utilize detection of such beacons and/or measurements made on such beacons in many ways. For example, the beacons may be used to geographically locate a user device in a particular area, to decide which access node that should serve a particular user device and/or to perform channel estimation.
Such uplink beacons can be narrowband or wideband in the frequency domain, in accordance with the number of contiguous subcarriers allocated for each user device. The user device allocation for uplink beacons can be signalled by the network via at least one access node e.g. by use of a DownLink (DL) control channel.
The rate at which a given user device transmits UL beacons can depend on many factors, and may cause problems. If, for example, the UL beacon transmission rate for a particular user device is low, the position of the user device may change significantly without the network being aware of such a change in position. Then, the network will not be able to reach the user device, e.g. in case there is DL data to be sent, since the access node that was previously able to connect to the user device is no longer able to do so. The downlink reachability will then have to be re-established again after the user device has transmitted the next UL beacon. Thus, some delay will here be incurred before the downlink reachability is restored.
Thus, the allocation of UL beacon and/or reference signal resources performed by the network may respond poorly to the needs of at least one particular user device at a specific time and location. This is for example problematic in situations where the user device suddenly changes from a static non-moving state to a moving state, or vice-versa. In such problematic cases, conventional solutions rely on the network for detecting that some performance metric is degrading. In other solutions, the user device measures and reports back to the network such performance metric degradation. The network must then react based on such degrading performance metric by increasing or decreasing the rate for transmission of UL beacons accordingly. The hereby provided reaction time between a change for the user device and the corresponding change in UL beacon transmission rate performed by the network is too long for many situations in the network.